The Judas window (1938)

A man wakes beside an arrow-pierced body in a locked study and seems to have no possible defence. Carter Dickson, John Dickson Carr’s pseudonym, lets Sir Henry Merrivale argue the case in court, where the physical evidence must withstand competing explanations. A particularly good choice if you enjoy a clearly bounded problem being examined from several angles. The courtroom sparring is part of the pleasure.